Sound and vibration isolating mount for an outboard motor

ABSTRACT

Disclosed herein is a sound and vibration isolating arrangement for an outboard motor having a marine propulsion unit mounted rearwardly of the steering axis of the outboard motor. The mounting arrangement includes a pair of mounts secured to the propulsion unit in a vertically spaced relation approximately in alignment with the neutral or roll axis of the propulsion unit and rearwardly of or behind the drive shaft. Each mount includes a crossbar which is supported by a resilient bushing within a casing and which has ends extending outwardly from the casing transversely to the direction of motion of the propulsion unit.

United States Patent [72] Inventor Dale L. Taipale Waukegan, Ill.

[21 Appl. No. 856,990 [22] Filed Sept. 11,1969 [45] Patented Aug. 17,1971 I73 I Assignee Outboard Marine Corporation Waukegan, lll.

[54] SOUND AND VIBRATION ISOLATING MOUNT FOR AN OUTBOARD MOTOR 15Claims, 7 Drawing Figs.

[52] US. Cl... 115/17 [51] Int. Cl ....B63h 21/26 [50] Field ot'Search115/18, 17;

[56] References Cited UNITED STATES PATENTS 2,630,991 3/l 953 Long 248/4ll5/l8 248/15 2,740,368 4/1956 lrgensetal.... 3,432,127 3/1969 PhilippPrimary Examiner-Andrew H. Farrell Attorneyslohn W. Michael, Gerrit D.Foster, Bayard H.

Michael, Paul R. Puerner, Joseph A. Gemignani, Andrew 0. Riteris,Spencer B. Michael and Robert E. Clemency ABSTRACT: Disclosed herein isa sound and vibration isolating arrangement for an outboard motor havinga marine propulsion unit mounted rearwardly of the steering axis of theoutboard motor. The mounting arrangement includes a pair of mountssecured to the propulsion unit in a vertically spaced relationapproximately in alignment with the neutral or roll axis of thepropulsion unit and rearwardly of or behind the drive shaft. Each mountincludes a crossbar which is supported by a resilient bushing within acasing and which has ends extending outwardly from the casingtransversely to the direction of motion of the propulsion unit.

PATENTED AUG] 7197: 3 599,594

sum 2 0F 3 INVIN'FQR. 0446 L. 777/P49LE Ev W Am /W*M ATTORNEY$Pmmanwsmsn 3,599,594

SHEET 3 0F 3 'NVENTQQ -5 4. 7740 04:

ATTORNI1$ SOUND AND VIBRATION ISOLATING MOUNT FOR AN OUTBOARD MOTORBACKGROUND OF THE INVENTION The isolation from a boat hull ofv sound andvibration emanating from a propulsion unit of an outboard motor hasconventionally been accomplished by using a plurality of mounts as shownin U.S. Pat. Nos. 2,740,368, 2,910,007, 2,91 1,963 and 3,002,489.

SUMMARY OF THE INVENTION The sound and vibration isolation mountingarrangement of this invention utilizes one pair of resilient mounts toisolate the I v vibrations due to violent motions of the outboard motor.

Other objects and advantages of the invention will become apparent fromthe following description when read in connection with the accompanyingdrawings, in which:

FIG. I is a side view in elevation of an outboard motor with portionsbroken away to show the sound and vibration mounting arrangement.

FIG. 2 is a top view of a portion of the outboard motor partly brokenaway to show the upper mount.

FIG 3 is a side view in section of the upper mount in the propulsionunit.

FIG. 4 is an exploded view in perspective of the upper mount and upperyoke.

FIG. 5 is a top view in section of the lower mount positioned within thedrive shaft housing of the propulsion unit.

FIG. 6 is a side view in section of the lower mount.

FIG. 7 is an exploded view in perspective of the lower mount, supportingbracket and lower resilient snubber.

DESCRIPTION OF THE INVENTION drive shaft housing 30 having a drive shaftindicated at 32 and a lower unit gearcase 34. As will be explained ingreater detail hereinafter, the drive shaft housing 30 also includes amounting opening which is shown at 36 in FIG. I and which is locatedsomewhat above the gearcase 34.

The propulsion unit 24 is supported for pivotal steering movement on theswivel bracket 16 by means of a kingpin assembly 38 which includes apivot shaft 40 journaled in the bushings 22 provided in the swivelbracket aperture 20. Secured to the upper end of the pivot shaft 40 isan upper yoke 42 having a forwardly extending steering bracket 44 andrearwardly extending arms 46. Secured to the lower end of the pivotshaft 40 is a lower support yoke 48 having a splined aperture 50 mountedon a splined portion 52 on the pivot shaft 40 and retained thereon by anut 54.

The propulsion unit 24 is subject to various vibrations includingtorsional or oscillatory vibrations set up by the power impulses ofthe'engine in the power head 26. These torsional vibrations occur abouta neutral or roll axis which is generally indicated at 56 and whichextends approximately vertically through the center of mass of thepropulsion unit 24 and is generally spaced from the drive shaft 32 onthe same side as the pistons 28 in the cylinder block. Forward andreverse thrust forces are also set up in the propulsion unit 24 by themotion of a propeller 58 mounted on a stub shaft 60 in the lower unitgearcase 34. The stub shaft 60 is driven off of the drive shaft 32 bymeans of a forward and reversing gear assembly generally indicated at62.

In accordance with the invention, the vibrations set up in thepropulsion unit 24 are isolated from the boat hull and the propulsionthrust is simultaneously transmitted from the propulsion unit 24 to theswivel bracket 16 and then to the boat hull by means includingvertically spaced upper and lower resilient mounts 64 and 66 connectedbetween the propulsion unit 24 and the kingpin assembly 38 rearwardly ofthe drive shaft indicated at 32. The upper mount 64 and the lower mount66 also provide the principal support for the weight of the propulsionunit 24 and transmit the thrust force of the propeller 58 to the boathull. When a forward thrust force is produced by the propeller 58, theprincipal force acting on the upper mount 64 will occur on the forwardside and on the lower mount 66 on the aft side.

More particularly, the upper mount 64, as seen in FIGS. 2, 3 and 4,includes a bushing 68'formed from a resilient material such as naturalrubber and an insert or crossbar 70 having at each end a threadedmounting hole 72. The crossbar 70 is encircled or embedded in thebushing 68 and extends outwardly from each end of the bushing 68. Meansare provided for connecting the upper mount 64 to the propulsion unit 24in the form of a casing 74 having mounting holes 76 which encloses andis secured to the outer surface of the bushing 68. Bolts 78 are insertedthrough the mounting holes 76 in the casing 74 and are screwed into thethreaded holes 79 provided in the drive shaft housing 30. The mount 64is also connected to the yoke 42 by means of mounting screws 80 insertedthrough holes 82 provided at the ends of arms 46 and screwed into holes72 in the crossbar 70. The crossbar 70 extends transversely to thedirection of thrust of the propulsion unit and approximatelytransversely to the neutral axis 56.

It is desirable that the bushing 68 in the upper mount 64 be soft inorder to damp vibrations emanating from the propulsion unit. This isaccomplished by means of a number of holes 84 and L-shaped slots 85provided in the bushing 68 in a generally parallel relation to thecrossbar 70. The holes 84 are provided on the forward side of thebushing 68 and the L- shaped slots 85 are provided only on the upper andlower sides of the aft side of the bushing 68 since the principal thrustforce on the upper mount 64 occurs on the forward side of the bushing68.

The transmission of local vibrations from the power head 26 to the yoke42 is prevented by means of a snubber sleeve 86 provided on the endofeach of the arms 46. The sleeves 86 are formed from a resilientmaterial such as Neoprene and act to prevent metal-to-metal contactbetween the power head 26 and the arms 46 of the yoke 42.

The lower mount 66, as seen in FIGS. 5,6 and 7, includes a resilientbushing 88 formed from a resilient material such as natural rubber andan insert or crossbar 90 having at each end mounting holes 92. Thecrossbar 90 is encircled or embedded in the bushing 88 and extendsoutwardly from each end of the bushing 88. A casing or sheel 94 enclosesand is secured to the outer surface of the bushing 88 and is coveredwith a resilient shield or coating 96. The lower mount 66 is connectedto the lower end of the drive shaft housing by being positioned in theopening 36 provided in the drive shaft housing 30. The crossbar 90extends transversely to the direction of thrust of the propulsion unitand approximately transversely to the neutral axis 56.

Means are provided to limit transverse movement of the lower mount 66 inthe opening 36 in the form of a flange 98 provided at one end of theopening 36 and a retainer plate 100 provided at the other end of theopening 36. The lower mount 66 is connected to the lower support yoke 48by means of bolts 102 which are inserted through the mounting holes 92in the crossbar 90 and nuts 104 which are screwed onto the bolts 102.

A snug fit is provided between the mount 66 and the housing 36 by meansof a resilient shield 96 molded on the outersion unit. This isaccomplished by means of a number of holes 106 and L-shaped slots 107located in a generally parallel relation to the crossbar 90. The holes106 are provided on the aft side of the bushing 88 and the slots 107 areprovided only on the upper and lower portion of the forward side of thebushing 88 since the principal thrust occurs on the aft side of thebushing 88.

In a preferred embodiment the lower mount 66 has twice the spring rateas the upper mount 64. If the mounts are used to'isolate vibrations in a85 or 1 l5-hp. motor, the lower mount 66 can have a spring rate ofapproximately 20,000 lbs./in. and the upper mount 64 can have a springrate of 10,000 lbs./in.

Due to the desirable softness of the bushings 68 and 88 on the reversethrust side, means are provided to mechanically connect the drive shafthousing 30 to the swivel bracket 16 to minimize deflection of thepropulsion unit 24 with respect to the swivel bracket 16 when reversethrust is produced by the propeller 58. Such means, as shown in FIG. hisin the form of strap 108 which encircles the swivel bracket 16 issecured to the drive shaft housing 30 by pin 1 10.

Means are also provided for preventing transmission of mechanicalvibration between the lower support bracket or yoke 48 and the lowerportion of the drive shaft housing 30 in the form of a resilient snubber112 positioned between the yoke 48 and the outer surface of the driveshaft housing 30. The lower snubber 112 is formed from a resilientmaterial such as Neoprene and has a pair of enlarged sections 1 l4positioned to engage the drive shaft housing 30. The snubber 112 issecured to the yoke 48 by means of brackets 116 embedded in each end ofthe snubber and have apertures 118. The brackets 116 are positioned onthe bolts 102 between the end of the crossbar 90 and the yoke 48 tolocate the snubber between the yoke 42 and the drive shaft housing 30.

Various of the features of the invention are set forth in the followingclaims.

What I claim ls:

1. The combination in an outboard motor of a transom bracket, a swivelbracket mounted on said transom bracket for vertical tilting movement, apropulsion unit, a crossbar disposed transversely to the direction ofmotion of said propulsion unit and connected to one of said swivelbracket and said propulsion unit, and a resilient bushing encirclingsaid crossbar and connected to the other of said swivel bracket andpropulsion unit.

2. A combination according to claim I wherein said crossbar is connectedto said swivel bracket and said bushing is connected to said propulsionunit.

3. A combination according to claim 1 wherein said propulsion unitincludes a drive shaft housing having'a vertically disposed drive shaft,said crossbar being disposed rearwardly of said drive shaft.

4. A combination according to claim 1 including a casing enclosing saidbushing, said casing being connected to said propulsion unit.

5. A combination according to claim 1 including a second crossbardisposed transversely to the direction of motion of said propulsion unitand connected to one of said swivel bracket and said propulsion unit,and a second resilient bushing encircling said second crossbar andconnected to the other of said swivel bracket and said propulsion unit.

6. A combination according to claim 5 wherein said crossbars areconnected to said swivel bracket and said bushings are connected to saidpropulsion unit.

7. A combination according to claim 5 including a casingenclosing eachof said bushings, said casings being connected to said propulsion unit.

8. A combination according to claim 5 wherein said propulsion unitincludes a drive shaft housing having a drive shaft, said crossbarsbeing disposed rearwardly of said drive shaft.

9. A combination according to claim 8 wherein one of said casings isconnected to one end of said drive shaft housing and the other of saidcasings is connected to the other end of said drive shaft housing.

10. A combination according to claim 5 wherein each of said bushingsincludes a number of holes located parallel to said crossbar.

11. A combination according to claim 5 wherein one of said bushings hastwice the spring rate of the other of said bushings.

12. A combination according to claim 8 including means for preventingtransmission of mechanical vibrations from said drive shaft housing tosaid swivel bracket.

13. The combination in an outboard motor of a transom bracket, a swivelbracket mounted on said transom bracket for vertical tilting movement, apropulsion unit including a power head, a drive shaft housing includinga drive shaft, and a lower unit gearcase, means for pivotally mountingsaid propulsion unit on said swivel bracket for steering movementrearwardly of said swivel bracket and including an upper and a loweryoke, an upper resilient mount connecting said propulsion unit to saidupper yoke and a lower resilient mount connecting said propulsion unitto said lower yoke, each of said mounts including a bushing and acrossbar embedded in said bushing and disposed transversely to thedirection of motion of said propulsion unit.

14. A combination according to claim 13 wherein said propulsion unitincludes a neutral axis extending through said power head, drive shafthousing and lower unit gearcase in a spaced relation to said driveshaft, said mounts being positioned substantially transversely to saidneutral axis.

15. A combination according to claim 13 including means for mechanicallyconnecting said drive shaft housing to said swivel bracket to minimizedeflection onreverse thrust of said propulsion unit.

1. The combination in an outboard motor of a transom bracket, a swivelbracket mounted on said transom bracket for vertical tilting movement, apropulsion unit, a crossbar Disposed transversely to the direction ofmotion of said propulsion unit and connected to one of said swivelbracket and said propulsion unit, and a resilient bushing encirclingsaid crossbar and connected to the other of said swivel bracket andpropulsion unit.
 2. A combination according to claim 1 wherein saidcrossbar is connected to said swivel bracket and said bushing isconnected to said propulsion unit.
 3. A combination according to claim 1wherein said propulsion unit includes a drive shaft housing having avertically disposed drive shaft, said crossbar being disposed rearwardlyof said drive shaft.
 4. A combination according to claim 1 including acasing enclosing said bushing, said casing being connected to saidpropulsion unit.
 5. A combination according to claim 1 including asecond crossbar disposed transversely to the direction of motion of saidpropulsion unit and connected to one of said swivel bracket and saidpropulsion unit, and a second resilient bushing encircling said secondcrossbar and connected to the other of said swivel bracket and saidpropulsion unit.
 6. A combination according to claim 5 wherein saidcrossbars are connected to said swivel bracket and said bushings areconnected to said propulsion unit.
 7. A combination according to claim 5including a casing enclosing each of said bushings, said casings beingconnected to said propulsion unit.
 8. A combination according to claim 5wherein said propulsion unit includes a drive shaft housing having adrive shaft, said crossbars being disposed rearwardly of said driveshaft.
 9. A combination according to claim 8 wherein one of said casingsis connected to one end of said drive shaft housing and the other ofsaid casings is connected to the other end of said drive shaft housing.10. A combination according to claim 5 wherein each of said bushingsincludes a number of holes located parallel to said crossbar.
 11. Acombination according to claim 5 wherein one of said bushings has twicethe spring rate of the other of said bushings.
 12. A combinationaccording to claim 8 including means for preventing transmission ofmechanical vibrations from said drive shaft housing to said swivelbracket.
 13. The combination in an outboard motor of a transom bracket,a swivel bracket mounted on said transom bracket for vertical tiltingmovement, a propulsion unit including a power head, a drive shafthousing including a drive shaft, and a lower unit gearcase, means forpivotally mounting said propulsion unit on said swivel bracket forsteering movement rearwardly of said swivel bracket and including anupper and a lower yoke, an upper resilient mount connecting saidpropulsion unit to said upper yoke and a lower resilient mountconnecting said propulsion unit to said lower yoke, each of said mountsincluding a bushing and a crossbar embedded in said bushing and disposedtransversely to the direction of motion of said propulsion unit.
 14. Acombination according to claim 13 wherein said propulsion unit includesa neutral axis extending through said power head, drive shaft housingand lower unit gearcase in a spaced relation to said drive shaft, saidmounts being positioned substantially transversely to said neutral axis.15. A combination according to claim 13 including means for mechanicallyconnecting said drive shaft housing to said swivel bracket to minimizedeflection on reverse thrust of said propulsion unit.